1. Field of the Invention
The present invention relates to a member having beads to be used to construct a car body.
2. Description of the Background Art
In an automobile, for the purpose of the protection of a passenger, members of a car body are equipped with concave or convex beads for absorbing an energy due to a crushing load exerted to them externally.
Such beads can be positioned in various different manners. For example, for a side member 103 inside an engine room 101 of a car 100 shown in FIGS. 1 and 2, beads 105 may be provided on edges as shown in FIG. 3(A), on side faces as shown in FIG. 3(B), or on both of these as shown in FIG. 3(C). In each of these cases, when the side member 103 is subjected to a crushing load in a direction A, the beads 105 function to prevent the side member 103 from bending or cracking, and to absorb an energy due to the crushing load by making the side member 103 to be crushed along the direction A.
Now, conventionally, the positions of such beads have been determined empirically, by an empirical formulae based on a size of a cross section of the member. (See, for example, "Occupant protection for frontal impact (Toyota) in Tenth ESV conference, 1986.)
However, the aforementioned empirical formulae determines the positions of the beads solely on a basis of the size of the cross section of the member, so that it is difficult to apply for a case in which a dynamical effect or a plasticity effect plays an important role. Also, this empirical formulae does not account for a case in which a member is attached to other member, so that it is almost always not applicable to a member having a complex shape.